The present invention relates to an image forming apparatus having therein a developing unit relating to image forming conducted by a copying machine of an electrophotographic type, a printer and a facsimile machine.
In recent years, the amount of toner used has been increased by spread of colorization and speeding up of an image forming apparatus, and thereby, members in the apparatus relating to image forming are soiled by scattered toner to increase frequency of adverse effects on image quality.
As a measure to solve this problem, there is disclosed a method wherein suction duct (scattering duct) 544 that sucks scattered toner and exhaust duct (air sending duct) 542 that sends in air are provided respectively on the upper side and at the lower side of developing unit 534, as shown in FIG. 3, an air current that flows from the exhaust duct to the suction duct is formed near a portion (developing nip portion) where the developing unit faces photoreceptor (image carrier) 531, and toner scattering from the developing unit is controlled by an air curtain and scattered toner is collected (for example, see Unexamined Patent Application Publication No. 11-327295).
However, in the aforesaid technologies, although there is an effect for cooling of developing roller 541, temperature rise in the apparatus caused by speeding up of the apparatus and temperature rise in the developing unit caused by heat of compression (generation of heat by stress) of developing agents compressed by developer regulating plate 543 in the developing unit, especially by an increase of a rotation rate of a developing roller, have become a problem. Further, in the air flow in the technology in Unexamined Patent Application Publication No. 11-327295, scattered toner sticks to the developer regulating plate to disturb a flow of developing agents.